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FERTILIZERS 


PRICE  25  CENTS 


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FERTILIZERS 


-THEIR- 


SOURCE,  PURCHASE  AND  USE 

An   Elementary  Treatise  For  The 
Use  of  Farmers  and  Fruitgrowers 

BY 

CARROLL  B.  SMITH 


REDLANDS,  OAL  I 

CITROGRAPH   BOOK   PRESS 
190  3 


SiY^. 


OPTBIGHTED  1908, 

BY 

CABROLL    B.    SMITH 


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Redlands,  California.  CARROLL  B.  SMITH. 


.7979 


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TO  THE  'READER. 

This  pamphlet  is  written  expressly  for  those  who  are 
forced  to  use  fertilizers  from  year  to  year  and  yet  have  not 
the  time  to  investigate  the  subject  as  they  would  like  to. 
It  is  intended  to  be  brief  and  suggestive  of  thought  to  the 
reader  rather  than  complete  and  £nal. 

All  the  facts  and  deductions  contained  are  based  on  the 
highest  authorities  on  the  subjects  mentioned,  or  on  the 
results  of  actual  experience  in  California,  Those  interested 
are  advised  to  study  the  subjects  completely  in  such  volumes 
as  F,  H.  Storer's  ''Agriculture,''  3  Vols.;  L.  H.  Bailey's 
*'  Principles  of  Agriculture ;"  J.  P.  Roberts'  ''Fertility  oi 
the  Land ;"  C.  M.  Aikman's  "Measures  and  Manuring,'^ 
and  bulletins  of  the  U.  S.  Department  of  Agriculture. 

The  author  hopes  that  the  matter  here  given  will  aid 
the  farmer  to  choose  and  purchase  his  fertilizers  most 
wisely,  and  help  him  to  get  the  best  possible  results  from 
their  use.  There  is  no  £nal  authority  in  Nature.  She  is 
always  busy  making  exceptions ;  therefore,  every  farmer's 
problems  are  his  own  and  he  must  do  his  own  thinking. 
The  author  has  tried  to  present  only  well  established  facts 
and  general  PRINCIPLES.  A  fuller  knowledge  of  these, 
properly  applied,  will  lead  to  better  results  and  larger 
profits. 

Redlands,  California.  CARROLL  B.  SMITH. 


117979 


Essential  ^lant  Food. 


Each  of  the  three  plant  foods,  nitrogen,  phosphoric 
acid  and  potash,  are  called  essential  ingredients  in 
fertilizers,  as  they  are  the  elements  first  exhausted 
from  the  soil  by  plants.  There  are  eleven  other  ele- 
ments just  as  essential  to  perfect  plant  growth  as 
these  three,  but  the  soil  never  becomes  depleted  of 
them,  and  it  is  not  necessary  to  supply  them,  except 
in  rare  cases.  Sometimes  lime  and  iron  are  supplied 
to  the  soil,  though  not  regularly.  Lime  is  used  to 
set  free  nitrogen,  phosphoric  acid  and  potash,  when 
they  are  known  to  be  in  the  soil  in  insoluble  condi- 
tion and  in  large  amounts.  But,  as  lime  adds  no 
necessary  ingredient,  its  continued  use  alone  will  ex- 
haust a  soil.  If  a  soil  is  known  to  lack  iron,  this  may 
be  added  to  make  green  foliage  and  to  deepen  color 
of  oranges. 

If  a  soil  becomes  unproductive  under  good  tillage 
it  is  because  one  or  more  of  the  three  essential  plant 
foods  has  become  exhausted.  Hence  commercial  fertil- 
izers have  come  to  be  composed  of  various  amounts 
and  forms  of  nitrogen,  phosphoric  acid  and  potash. 
Commercial  fertilizers  are  simply  concentrated  forms 
of  plant  food.  A  good  top  soil  contains  every  element 

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essential  to  plant  growth  and  is  a  fertilizer,  but  it  is 
not  sufficiently  concentrated  to  pay  for  handling  and 
transportation. 

Each  of  the  three  plant  foods,  nitrogen,  phos- 
phoric acid  and  potash,  have  their  respective  market 
values  for  each  1  per  cent.,  or  unit,  of  20  pounds  to 
the  ton.  If  a  ton  of  fertilizer  contains  3  per  cent,  pot- 
ash, that  means  60  pounds.  The  purchaser  v^ill  have 
to  know  the  market  value  and  the  source  of  the 
nitrogen,  phosphoric  acid  and  potash  before  he  can 
determine  the  value  of  a  ton  of  a  certain  analysis. 
The  source  is  very  important,  because  the  most  avail- 
able forms  have  the  highest  market  value.  Without 
this  knowledge,  a  certain  brand  may  sell  for  $40  a 
ton  and  another  worth  only  one-half  its  value  ($20 
per  ton)  may  sell  more  readily  for  $38. 

Each  of  the  three  essential  plant  foods  has  its 
special  part  to  do  in  the  building  of  the  plant.  One 
cannot  do  the  work  of  the  other.  As  an  illustration : 
Nitrogen  in  the  absence  of  potash  may  produce  a 
luxuriant  and  rapid  growth  but  it  will  be  weak  and 
broken  down  by  the  first  wind ;  add  potasli  and  that 
same  succulent,  weak  growth  will  be  matured  and 
have  strength  enough  to  carry  its  load  of  fruit. 
Potash  alone  will  not  produce  the  growth,  but  will 
mature  it.  Both  nitrogen  and  potash  have  many 
other  functions  to  perform. 

Phosphoric  acid,  or  phosphorus,  must  be  present 

7 


in  order  that  the  plant  may  assimilate  its  nitrogen. 
The  process  (osmosis)  by  which  nutrients  pass 
through  the  plant  from  cell  to  cell  is  facilitated  by 
the  presence  of  phosphoric  acid.  Phosphorus  is  nec- 
essary for  the  seed^s  embryo  development  and  for  the 
formation  of  chlorophyll  (the  green  coloring  matter 
of  plants). 

Thus,  while  the  essential  plant  foods  each  have 
many  independent  functions  to  perform,  they  are 
mutually  dependent  upon  each  other,  and  mutually 
helpful  in  the  building  of  the  plant  tissue. 

The  condition  of  the  soil  may  be  such  that  the 
purchase  of  only  one  fertilizing  element  is  necessary, 
and  since  the  sources  of  nitrogen  and  phosphoric 
acid  and  their  functions  are  so  many  and  varied,  the 
question,  *^  What  fertilizer  to  use, '^  and  ^*  How  to  pur- 
chase it  most  economically,^^  is  of  vital  interest  to 
the  farmer  and  one  difficult  to  solve. 


SOURCE   OF  FERTILIZERS. 

THE  SOURCES  OF  NITROGEN. 

Nitrogen  may  be  obtained  from  these  sources : — 
Air,  ammonia,  nitrates  and  animal  matter.  In  cer- 
tain forms  of  animal  matter,  such  as  hoofs,  horns, 
coarse  bone,  leather  and  wool  waste,  the  nitrogen 
becomes  available  too  slowly  to  be  of  much  value. 
But  as  green  manure,  ammonia,  nitrates,  blood,  fine 

8 


bone,  tankage,  or  blood  and  bone,  fish,  and  finely 
ground  and  screened  guano,  the  nitrogen  is  in  good 
form  and  soon  beeomes  available. 

As  these  forms  require  different  lengths  of  time  to 
become  available,  judgment  must  be  used  in  their 
application.  Nitrate  of  soda  and  sulphate  of  ammo- 
nia dissolve  almost  immediately  in  water,  so  the  full 
amount  of  a  year's  supply  should  not  be  applied  at 
once,  as  some  will  be  sure  to  be  lost  in  waste  water. 
Blood  and  bone,  as  a  source  of  nitrogen  and  phos- 
phoric acid,  would  be  a  better  combination  than 
nitrate  and  bone.  Blood  and  fish  require  more  time 
to  become  available  than  nitrates,  and  bone  a  longer 
time  than  blood. 

**The  most  valuable  sources  of  organic  nitrogen, 
from  the  standpoints  of  uniformity  in  composition, 
richness  in  the  constituent,  and  availabilty,  are  dried 
blood,  dried  meat,  and  concentrated  tankage,  which 
are  produced  in  large  quantities  in  slaughter  houses 
and  rendering  establishments. '^  (Farmers'  Bulletin, 
No.  44,  U.  S.  Dept.  Agriculture.) 

The  most  concentrated  form  of  nitrogen  is 
ammonium  sulphate,  containing  about  19%  or  24% 
of  ammonia.  Nitrate  of  soda  contains  as  high  as 
16%  nitrogen,  blood  14%, hoof  and  horn  meal  14%, 
slaughter  house  tankage  from  5%  to  10%,  raw  bone 
31/2%,  bat  guano  9%,  sea  fowl  guano  12%.  There 
are  numerous  other   sources  of  nitrogen,  but   the 


above  are  those  most  generally  used.  The  contents 
as  given  are  in  terms  of  nitrogen  and  approximately 
the  maximum. 

NITRIFICATION. 

This  is  the  process  by  which  the  nitrogen  of 
organic  matter  is  changed  into  nitrates.  The 
ammonia  and  nitrogen  of  all  fertilizers  comes  from 
organic  matter,  and  all  organic  materials  contain 
more  or  less  of  those  substances  in  some  form. 
Nitrate  of  soda  in  the  nitrified  product  of  some 
organic  material,  whether  of  seaweed  or  animals,  is 
not  definitely  known.  Ammonium  sulphate  also  has 
an  organic  origin,  being  a  by-product  of  carbonizing 
works. 

Humus  (which  is  decayed  animal  or  vegetable 
matter)  is  the  main  source  of  the  plant's  nitrogen. 
When  organic  matter  is  applied  to  the  soil  it  must 
first  decay  and  then  nitrify  before  its  nitrogen  be- 
comes available  to  the  plant.  Tv\ro  processes  are 
necessary.  The  decay  is  produced  by  one  set  of 
bacteria  and  their  product  is  humus.  Then  the  sub- 
stance is  attacked  by  another  set  of  bacteria  which 
form  nitrates.  This  latter  process  is  nitrification. 
The  nitrates  thus  formed  are  water-soluble  and  can 
be  absorbed  by  root  hairs  into  plant  tissue. 

NITROGEN    FROM    AIR. 

Certain  plants  of  the  leguminosae  group  have 
power  to  accuraulate  nitrogen  from  the  air  to  the 

10 


process  of  growth.  Such  plants  are  the  lupins  and 
vetches.  Peas,  clover,  alfalfa  and  the  native  wild 
lupins  when  grown  as  catch  or  cover  crops  and 
ploughed  under  maintain  the  store  of  nitrogen  in 
soils.  But,  in  this  case,  as  with  other  organic  sub- 
stances, the  two  processes  of  decay  and  nitrification 
are  necessary  before  the  nitrogen  thus  gathered  be- 
comes available.  As  nitrogen  is  the  most  expensive 
of  all  fertilizing  elements  the  importance  and  economy 
of  a  green  cover  crop  ploughed  under  is  considerable. 

(See  also   ^*  Humus.'') 

SOURCES  OF  PHOSPHORIC  ACID. 

Phosphoric  acid,  or  phosphorous,  in  fertilizers,  is 
always  found  in  combination  with  other  elements. 
Usually  it  is  obtained  from  bone  or  phosphate  rocks. 
As  rock  it  cannot  become  readily  available  without 
treatment  with  sulphuric  acid.  As  bone,  unacidu- 
lated,  it  must  be  very  finely  ground  to  be  available, 
and  when  thus  ground  is  undoubtedly  the  best  form 
for  citrus  culture,  as  it  is  all  equally  available  and  its 
ability  to  rot  or  ferment  has  not  been  destroyed  by 
the  acid. 

ACIDULATED  PHOSPHATES. 

These  are  made  by  treating  bone  or  phosphate 
rock  with  sulphuric  acid.  Their  value  may  vary 
according  to  the  amount  of  acid  used  by  the  manu- 
facturer.   If  800  pounds  of  acid  were  used  with  1200 

11 


pounds  of  bone  or  rock,  it  would  be  a  40%  acidula- 
tion,  as  800  is  40%  of  2000  pounds. 

In  acidulated  goods,  whether  rock  or  bone,  there 
are  always  three  forms  of  phosphoric  acid— a  soluble 
form,  a  ''  reverted ''  form,  and  an  insoluble  form.  The 
last  is  of  no  commercial  value.  The  ^'reverted ^*  is  of 
doubtful  value,  as  it  has  to  first  undergo  a  chemical 
change  before  becoming  available.  The  soluble  is 
immediately  available.  A  dealer  giving  an  analysis 
should  not  mention  the  amount  of  insoluble  phos- 
phoric acid,  as  it  is  confusing.  An  insoluble  portion 
is  necessary  in  order  to  obtain  the  soluble,  but  does 
not  add  value  to  the  fertilizer.  State  laws,  as  a  rule, 
allow  the  reverted  to  be  estimated  as  available  with 
the  water-soluble,  so  that  the  soluble  and  reverted 
forms  constitute  the  phosphoric  value  of  a  fertilizer. 

It  must  be  remembered  that  in  using  acidulated 
goods  (bone  or  rock)  if  an  abundance  of  lime  be 
present  in  the  soil,  the  soluble  form  of  phosphoric 
acid  unites  chemically  with  the  lime  and  is  made 
again  insoluble  as  if  it  had  never  been  treated.  Iron, 
and  alumina,  and  other  bases,  produce  the  same 
effect  on  acidulated  phosphates.  The  reversion,  how- 
ever, depends  on  the  amount  of  acid  used  by  the 
manufacturer  and  the  quantity  of  lime,  iron,  etc.,  in 
the  soil. 

STEAMED  BONE. 

Steaming  bones  removes  the  fats  and  gelatines, 
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thus  facilitating  decay  and  availability,  as  such  bone 
can  be  ground  finer  than  raw  bone,  and  thus  becomes 
more  subject  to  the  attack  of  soil  moisture  and 
various  dissolving  agents. 

Raw^  bone  contains  from  3%  to  4^%  nitrogen  and 
about  22%  or  23%  phosphoric  acid.  Steaming  reduces 
the  nitrogen  and  correspondingly  increases  the  phos- 
phoric acid,  so  that  steamed  bone  may  run  as  low  as 
1%  nitrogen  and  as  high  as  25%  or  30  %  phosphoric 
acid.  The  best  effect  from  the  phosphoric  acid  of 
steamed  bone  is  had  when  the  bone  is  used  in  connec- 
tion with  some  ammoniate  such  as  blood,  or  blood 
and  bone,  or  manure.  Nitrogen  or  ammonia  increases 
the  efficiency  of  phosphoric  acid,  and  for  this  reason 
phosphoric  acid  from  animal  or  vegetable  sources  is 
regarded  as  the  best,  the  most  effective  and  the  most 
readily  available  form. 

THOMAS  PHOSPHATE  SLAG   ( POWDER). 

Thomas  slag,  a  product  of  iron  furnaces,  is  a 
good  source  of  phosphoric  acid,  though  not  so  gene- 
rally used  as  bone  or  rock.  This  material  has  to  be 
finely  ground  to  be  of  value,  as  it  is  not  acidulated. 
It  will  analyze  as  high  as  20%  phosphoric  acid. 
Thomas  slag  also  contains  much  lime,  which  fact 
should  be  considered  when  it  is  used  in  presence  of 
ammonium  sulphate,  or  bam  manures,  as  the  lime  will 
drive  off  the  ammonia.  One  brand  offered  for  sale  in 
Los   Angeles    contains    17.28  %    phosphoric    acid, 

13 


46.20%  lime,  and  iron  oxide  18.37%.  It  may  be 
used  to  best  advantage  on  trees  which  have  made 
strong,  nitrogenous  grov^th  at  the  expense  of  fruit 
productiDn,  and  also  on  peaty  soils,  poor  in  lime. 
Water  will  not  dissolve  slag,  therefore  it  should  be 
put  in  as  deeply  as  possible. 

PHOSPHATE  GUANOS. 

The  guanos  of  bats  and  sea  fowl  are  also  valuable 
sources  of  phosphoric  acid.  These  materials,  how- 
ever, vary  in  analysis  very  much.  Each  consignment 
should  be  analyzed  and  its  price  based  on  its  con- 
tents. The  first  shipments  from  a  guano  deposit  are 
the  richest  and  most  valuable,  but  deteriorate  as  the 
deposit  is  drawn  upon. 

CHEAPEST  FORM  OF  PHOSPHORIC  ACID. 

The  Pennsylvania  State  Department  of  Agricul- 
ture, in  Bulletin  No.  94,  gives  the  results  of  12  years' 
experiments  with  phosphates,  both  acidulated  and 
unacidulated,  and  seems  to  show  conclusively  that 
the  best  form  in  which  to  purchase  phosphoric  acid 
is  the  untreated  bone  or  rock.  This  is  only  on  condi- 
tion that  there  is  plenty  of  organ  icmatter,  or  humus- 
forming  material,  in  the  soil. 

Under  such  conditions  (with  humus  in  the  soil) 
finely  ground  rock  (unacidulated)  gave  better  results 
than  acidulated  rock  or  bone.  This  was  from  the 
standpoint  of  both  original  cost  of  material  and  the 


results  obtained,  and  was  true  of  all  crops  tried, 
except  wheat.  Unacidulated  fertilizers  always  con- 
tain more  phosphoric  acid  than  the  same  fertilizers 
acidulated,  as  the  weight  of  the  acid  used  displaces 
some  of  the  material,  and  if  organic  matter  is  used 
with  the  former,  the  conditions  thus  created  in  the 
soil  give  it  additional  life  which  takes  the  place  of 
acidulation,  and  results  in  greater  fertility.  A  num- 
ber of  lay  experiments  and  actual  practice  in  Cali- 
fornia agree  with  the  results  of  the  Pennsylvania 
State  Experiment  Station.  Where  there  was  little  or 
no  humus-forming  material  in  the  soil,  acidulated 
forms  gave  the  best  results. 

SOURCES  OF  POTASH. 

Potash  is  found  as  a  chloride,  or  muriate,  as  a 
sulphate,  and  in  a  crude  form  called  kainit.  The 
latter  contains  12^2%  actual  potash.  The  muriate 
and  sulphate  analyze  about  50%  actual  potash. 
The  Stassfurt  mines  of  Germany  supply  the  most  of 
this  product. 

The  potash  of  manufactured  fertilizers  is  seldom 
all  animal  matter.  All  forms  dissolve  readily,  so 
there  is  no  danger  of  buying  potash  in  unavailable 
form.  It  takes  about  two  pounds  of  sulphate,  or 
muriate,  of  potash  to  make  one  pound  actual  potash, 
or  10%  sulphate  to  make  5%  ''actual.'' 

Wood  ashes  and  stable  manure  are  also  sources 
of  potash,  obtainable  however,  in  very  limited  quan- 

15 


titles.  Wood  ashes,  unleached,  will  contain  from 
4%%  to  7%  potash:  stable  manure  contains  about 
0.4%  potash. 

The  sulphate  of  potash  is  the  best  form  in  which 
to  purchase.  It  has  no  ill  effects  on  many  plants, 
while  the  muriate  or  chloride  form  does.  The  sul- 
phate can  also  be  used  as  a  *^  fixer''  of  ammonia  in 
stables  and  manure  pits,  while  the  muriate  might 
cause  the  escape  of  ammonia. 

AVAILABILITY. 

Buyers  of  fertilizers  should  always  know  the 
source  and  form  of  the  different  plant  foods.  This 
knowledge  and  the  results  obtained  will  determine 
their  availability.  Nitrogen  from  nitrate  of  soda  is 
the  most  available  form  of  any.  Nitrogen  from 
blood  is  more  available  than  that  from  raw  bone. 

Phosphoric  acid  from  acid  phosphates  (rock  or 
bone)  is  more  soluble  than  the  non-acid  phosphates. 

Steamed  bone  finely  ground  is  more  soluble  than 
raw  bone.  The  phosphoric  acid  from  tankage  is 
more  available  than  that  from  raw  bone.  Both  the 
nitrogen  and  phosphoric  acid  as  found  in  animal 
tankage  and  guanos,  finely  ground,  are  very  avail, 
able  forms. 

Soil  moisture,  root  acids  and  fermentation  are 
the  dissolving  agents  in  all  soils.  The  high  tempera- 
tures of  summer  increase  their  action,  and  hence  the 
availability  of  fertilizing  elements. 

16 


Roots  cannot  take  up  plant  food  unless  it  is  pro- 
vided in  solution,  and  different  forms  of  fertilizers 
respond  differently  to  these  dissolving  agents.  Fine 
grinding  is  very  important.  As  a  rule,  organic  forms 
are  most  available.  There  are  some  exceptions,  such 
as  sulphate  of  ammonia,  nitrate  of  soda  and  the  acid 
phosphates.  The  latter  act  best  in  soils  that  do  not 
contain  enough  lime  or  iron  or  other  bases  to  cause 
rapid  reversion  to  insolubility. 

If  the  farmer  knows  the  source  and  form  of  the 
nitrogen  and  phosphoric  acid,  he  has  a  guide  to  their 
availability. 

All  forms  of  potash  as  usually  purchased  in  fertil- 
izers are  readily  dissolved  and  there  is  no  danger  oi 
buying  this  ingredient  in  an  insoluble  form. 

Some  substances,  as  barnyard  manure  and  lime, 
make  all  fertilizers  more  available,  but  they  do  not  add 
plant  food  to  the  soil  in  the  amounts,  nor  as  fast  as 
required,  and  their  use  alone  will  in  time  exhaust  a 
soil.  Especially  is  this  true  of  lime.  Better  results 
will  be  obtained  by  using  commercial  fertilizers  with 
manure  than  by  using  either  one  alone,  because  the 
conditions  of  availability  will  be  increased.  (See  also 
'^Cultivation  and  Fertilizers.**) 

INSOLUBILITY  DESIRABLE. 

It  is  well  known  that  the  nitrates  may  easily  be 
lost  by  leaching,  because  they  are  soluble.  This  is 
not  the  case  with  the  phosphates,  or  phosphorous 

17 


compounds,  as  these  are  always  insoluble  even  in  the 
most  fertile  soils.  Numerous  analyses  of  the  *^run 
off  ^  waters  show  this.  The  nitrates  being  always 
available  to  the  plant,  stimulate  its  feeding  powers 
and  force  it  to  act  on  such  insoluble  compounds  as 
the  phosphates,  which,  in  turn,  by  yielding  slowly, 
regulate  growth  and  maintain  for  a  longer  time  the 
soirs  productive  power. 

It  can  readily  be  seen  that  the  loss  would  be 
many  times  greater  if  the  phosphates  and  other  com- 
pounds were  soluble  as  well  as  the  nitates. 

The  phosphoric  acid  of  soils  is  practically  always 
insoluble.  This  is  true  of  new  lands,  the  richest  and 
most  productive  known.  It  is  nature^s  method.  All 
fertile  soils  contain  such  bases  as  lime,  iron  and  others 
that  hold  phosphorous  in  insoluble  compounds  from 
w^hence  it  is  released  only  by  the  processes  of  plant 
growth  and  the  chemical  activities  of  fertile  soils. 


THE  PURCHASE  OF  FERTILIZERS. 

Fertilizers  should  be  purchased  by  the  unit  of 
plant  food  contained,  with  due  consideration  of  its 
source,  and  not  simply  by  the  ton  or  brand,  as  is 
usually  the  case.  Each  twenty  pounds  of  a  ton  is 
called  one  unit  or  1%;  5%  is  five  units  or  one  hun- 
dred pounds.  Growers  often  ask,  ''Can  we  afford  to 
pay  $40  per  ton  for  fertilizer?'*  It  depends  entirely 
upon  the  amount  and  source  of  plant  food  contained. 

18 


We  cannot  afford  $40  per  ton  for  low  grade  analysis, 
but  can  well  pay  $40  for  high  grade-goods.  Freight, 
sacking,  storage  and  handling  are  fixed  expenses  on 
low  or  high  grades.  Therefore,  high  grades  are 
cheapest. 

The  way  to  figure  the  difference  in  value  between 
several  brands  of  fertilizer  is  as  follows: 

Take  nitrogen  at  16  c.  per  pound,  phosphoric 
acid  at  5^  c.  per  pound,  potash  (actual)  at  6  c.  per 
pound. 

(Note. — These  values  are  based  on  the  cost  of 
nitrate  of  soda,  and  sulphate  of  potash  laid  down  in 
inland  California  points.) 

Remember  that  1  %  or  one  unit  of  a  ton  is  20 
pounds. 

If  ammonia  is  given  instead  of  nitrogen  you  can 
find  its  equivalent  in  nitrogen  by  multiplying  by 
.825%;  for  instance,  5^%  ammonia  equals  4.54% 
nitrogen. 

Do  not  multiply  the  percentage  of  ammonia  by 
20  and  then  by  16c.  as  it  then  would  read  too  much, 
but  must  first  be  reduced  to  terms  of  nitrogen. 

Also  do  not  confuse  sulphate  of  potash  with  the 
actual  (or  K2O)  potash.  The  sulphate  usually  runs 
about  49  %  actual.  So,  in  round  numbers,  it  takes  2 
pounds  of  sulphate  to  make  one  pound  actual,  or  2% 
sulphate  to  make  1  %  actual. 

19 


Allowance  also  must  be  made  for  phosphoric  acid 
if  it  is  derived  from  raw  bone.  It  is  then  worth 
about  2c.  per  pound  while  if  taken  from  steamed 
bone  would  be  worth  fully  5c.  per  pound.  In  acidu- 
lated  goods  the  phosphoric  acid  is  in  three  different 
forms,  with  market  values  from  2c.  up  to  5V2C.  per 
pound:  the  water-soluble  being  worth  5%c.  per 
pound,  the  insoluble,  2c.  per  pound. 

The  source  is  just  as  important  a  consideration 
as  the  quantity  when  considering  the  value.  Both 
the  quantity  of  plant  food  (that  is,  of  nitrogen, 
phosphoric  acid  and  potash)  and  its  source,  which 
determines  its  form,  are  really  the  only  factors  which 
compose  the  value  of  a  ton  of  fertilizers. 

Here  are  two  analyses  of  different  total  value 
which  will  illustrate  the  foregoing: 

ANALYSIS    I. 

Nitrogen  in  terms  of  ammonia,  5  %. 
Equivalent  in  nitrogen  (5X.825) 

4.13  %  X20=82.60  pounds  at  16c $13.21 

Phosphoric  acid  (from  steamed  bone) 

12X20=240  pounds  at  5y2C 13.20 

Equivalent  to  bone  phosphate  26% 
Potash  (actual,  K2O) 

3X20=60  pounds  at  6c 3.60 

Sulphate  of  potash,  5.9% 

Total  value  of  ton... $30.01 

20 


Note.— No  account  is  taken  of  either  the  26%  of 
bone  phosphate  or  of  the  5  %  sulphate  of  potash  as  they 
are  only  repetitions  of  the  12%  phosphoric  acid  and 
the  3%  actual  potash,  respectively. 

ANALYSIS  n. 
Nitrogen  in  terms  of  ammonia,  5^%. 
Equivalent  to  nitrogen  (5%X.825) 

4.54X20=90.80  pounds  at  16c $14.53 

Phosphoric  acid  (from  raw  bone) 

13X20=260  pounds  at    2c $5.20 

Equal  to  bone  phosphate,  31% 
Potash,  (actual,  K2O) 

4X20=80  pounds  at    6c $4.80 

Sulphate  of  potash,  7.95%. 

Total  value  of  ton $24.53 

Although  Analysis  II  is  higher  in  its  percentage 
of  plant  food,  the  form  of  the  phosphoric  acid  is 
against  it  and  cheapens  it  so  much  that  the  total 
value  of  the  ton  is  considerably  less. 

Either  of  these  analyses  might  be  offered  to  the 
grower  for,  say,  $35  per  ton  and  No.  1  would  be  the 
best  buy  for  the  grower,  and  No.  2  the  best  sale  for 
the  agent  or  manufacturer. 

It  is  quite  possible  for  the  nitrogen  to  be  in  cheap 
form  also  and  worth  considerably  less  than  16c.  per 
pound.  The  nitrogen  from  raw  bone  is  worth  less 
than  that  from  blood,  or  bird  guano,  or  tankage. 

21 


So  the  value  of  a  ton  of  fertilizer  is  based  upon 
the  source  or  form  of  the  nitrogen,  phosphoric  acid 
and  potash,  and  the  quantity  of  each. 

COST  OF    NITROGEN. 

Nitrate  of  soda,  96%  pure,  16%  nitrogen,  at  $50 
per  ton.  This  yields  307  pounds  of  nitrogen,  which, 
at  $50  per  ton,  equals  16.3c.  per  pound  or  $3.24  per 
unit  of  20  pounds. 

Dried  ground  blood,  analyzing  15%  nitrogen,  or 
301  pounds  at  $50  per  ton,  equals  16.6c.  per  pound, 
or  $3.32  per  unit.  From  horse  manure  containing 
,5%  nitrogen,  at  $2  per  ton,  equals  20c.  per  pound, 
to  say  nothing  of  the  phosphoric  acid  and  potash 
contained.  The  New  York  Experiment  Station  gives 
the  price  of  nitrogen  in  nitrate  as  15c.  per  pound,  in 
meat  and  blood  as  16c.  per  pound,  in  bone  and 
tankage  (ground)  as  16c.  per  pound. 

COST  OF    PHOSPHORIC  ACID. 

Steamed,  ground  bone  (not  acidulated)  at  $35 
per  ton,  containing  25%  phosphoric  acid  (500 
pounds)  equals  6c.  per  pound,  less  the  value  of  1% 
nitrogen  (20  pounds)  contained  in  steamed  bone  at 
16.4c.  per  pound  would  make  the  net  cost  of  phos- 
phoric acid  about  $1.10  per  20  pounds,  or  5Mjc.  per 
pound.  Thomas  Phosphate  Powder,  17%  phosphoric 
acid,  at  $22.50  per  ton,  would  cost  $1.30  per  unit, 
or  6V2C.  per  pound. 

22 


COST  OF  POTASH. 

The  sulphate  yielding  49%  actual  potash  can  be 
bought  for  $60  per  ton,  making  the  actual  potash 
cost  6c.  per  pound  or  $1.20  per  unit,  or  20  pounds 
of  a  ton. 

MOST  ECONOMICAL  FORM  OF  FERTILIZERS. 

If  the  price  of  nitrogen  is  the  same  in  nitrates, 
and  bone  and  blood,  the  cheapest  is  that  which 
becomes  available  just  as  fast  as  the  tree  wants  it, 
neither  faster  nor  slower.  Is  nitrate  too  quickly 
soluble  for  the  tree  to  use  all  of  it  before  a  part  of  it 
is  carried  away  by  waste  water?  Is  ground  bone 
too  slowly  available  or  blood  and  bone  just  right? 
Who  will  tell,  and  how?    It  is  a  fine  problem. 

If  a  form  of  plant  food  becomes  available  too 
rapidly,  the  moisture  holding  it  in  solution  rises  and 
evaporates,  leaving  this  soluble,  valuable,  food  on 
the  top  of  the  ground,  whence  it  is  partly  lost  by 
escaping  surface  waters,  and  part  carried  back  into 
the  soil  by  penetrating  moisture.  That  is  why  slow- 
running  water  gives  the  most  profitable  irrigation. 
A'Svaste  water'' right  on  one  ranch  from  another 
becomes  also  a  fertilizer  right,  provided  the  other 
man  fertilized. 

If,  however,  some  form  of  plant  food,  not  so 
quickly  soluble  in  running  water  as  nitrate  of  soda, 
and  yet  readily  soluble  by  soil  moisture  and  root 

23 


action,  is  used,  there  is  much  less  actual  loss  during 
a  season,  and  its  effect  is  more  sure  and  lasting.  Yet 
there  are  times  when  a  quick-acting  fertilizer  is 
needed.  This  would  then  be  the  most  economical 
form.  It  depends  upon  the  needs  at  the  time,  and 
the  farmer  should  know  enough  about  the  nature  of 
the  different  forms  of  plant  food  to  exercise  judgment 
in  the  selection. 


GENERAL  PURCHASING  PRINCIPLES. 

1.  The  market  value  of  every  brand  depends 
upon  the  amount,  or  percentage,  of  plant  food  con- 
tained. The  nitrogen,  phosphoric  acid  and  potash  each 
have  their  own  market  value  per  pound,  and  these 
must  be  known  to  the  grower  in  order  to  purchase 
economically. 

2.  Be  sure  the  food  elements  are  of  proper 
source  and  form  to  be  available  as  fast  as  wanted 
by  the  trees. 

3.  Purchase  high  grade  materials. 

EXAMPLE  OF  FERTILIZER  WORTH  $5.30  PER  TON. 

Fresh  water  mud,  2000  pounds,  contains: 

30  pounds  nitrogen  (1^2%)  at  16c $4.80 

41/2  pounds  phosphoric  acid  (.23% )  at  5V^c 23 

4y2   pounds    potash   (.23%)    at    6c 27 

$5.30 

24: 


EXAMPLE  OF    FERTILIZER    WORTH    $36  PER  TON. 

Eighteen  hundred  pounds  of  blood  and  bone, 
containing  7%  nitrogen  and  lOK  phosphoric  acid, 
added  to  200  pounds  sulphate  of  potash,  will  make 
one  ton  analyzing  as  follows: 

126  lbs.  nitrogen  (6.3%@16c) $20.21 

180  lbs.  phosphoric  acid  (9%@5i/2c) 9.90 

100  lbs. potash  (5%@6c.) 6.00 

$36.11 

ILLUSTRATION    NO.  I— A    HIGH  GRADE  FERTILIZER 
CONTAINING  NO  FILLER. 

ANALYSIS.  OBTAINED  FROM  LBS. 

Nitrogen  5^2% 1400  lbs.  raw  bone,  3.5% 

(110  lbs.)  nitrogen 49.00 

400  lbs. nitrate  soda  (96% 
pure— 16 %  nitrogen) 61 .44 


110.44 
Phosphoric  acid...  1400  lbs.  raw   bone,  23% 

16%  (322  lbs.)       phosphoric  acid 322.00 

Potash  5%  actual.200   lbs.    sulphate,    50% 

(100  lbs.)  actual  potash 100.00 

COST  OF  ABOVE  MATERIALS. 

1400  lbs.  bone  at  $30.00  per  ton $21.00 

400  lbs.  nitrate  at  $50.00  per  ton 10.00 

200  lbs.  sulphate  at  $60.00  per  ton 6.00 

2000  lbs.  Total $37.00 

25 


ILLUSTRATION  NO.  n— A  LOWER    GRADE    FERTILIZER 
CONTAINING  230  LBS.  FILLER. 

ANALYSIS.  OBTAINKD  FROM  LBS. 

Nitrogen  5% 1300  lbs.    raw   bone,    3.5% 

100  lbs.  nitrogen 45.00 

390  lbs.  blood,  14%  nitrogen.54.60 

99.60 
Phosphoric  acid...  1300  lbs.  bone,   23%   phos- 

15%,  299  lbs.        phoric  acid 299.00 

Potash  (actual)... 

2%,  40  lbs 80  lbs. sulphate 40.00 

COST  OF  ABOVE  MATERIALS. 

1300  lbs.  bone  at  $30.00  per  ton $19.50 

390  lbs.  blood  at  $50.00  per  ton 9.75 

80  lbs.  sulphate  of  potash  at  $60.00  per  ton     2.40 

1770 
230  filler 

2000  lbs.  Total $31.65 

Illustration  No.  I  shows  that  if  the  analysis  is 
high,  only  high  grade  materials  can  be  used.  Illus- 
tration No.  II  shows  that  if  the  analysis  is  low,  either 
low  grade  materials  or  fillers  were  used.  In  No.  II, 
high  grade  materials  up  to  1770  lbs.  were  used,  and 
their  value,  pound  for  pound,  is  the  same  as  in  No.  I. 
A  filler  used  v^ith  high  grade  materials  is  equivalent 
to  the  use  of  low  grade  goods  and  the  resulting 

26 


analysis  in  No.  II  shows  it.  Less  blood  and  bone 
could  have  been  used  in  No.  II,  and  more  filler,  but  the 
resulting  analysis  would  have  been  still  lower. 

If,  however,  the  fertilizer  is  acidulated,  the  per- 
centage of  plant  food  may  be  low,  as  the  weight  of 
the  acid  used  displaces  some  of  the  material,  yet  the 
fertilizer  should  be  considered  high  grade  on  account 
of  the  more  soluble  condition  of  its  phosphoric  acid. 
Here  the  better  form  of  plant  food  compensates  for 
the  smaller  quantity.  If  the  acid  phosphate  should 
revert  to  insolubility  on  account  of  the  lime  or  other 
bases  in  the  soil,  its  purchase  would  be  equivalent  to 
low  grade  materials,  as  the  advantage  of  greater 
solubility  is  largely  lost  and  the  total  amount  of 
phosphoric  acid  purchased  is  small. 

THE    **  SIMPLES^'    AND  HOME  MIXTURES. 

The  **  simples  *'  are  the  original  materials,  or  the 
bases  of  which  factory  mixed  fertilizers  are  composed. 
They  are  such  materials  as  nitrate  of  soda,  pure 
blood,  sulphate  of  ammonia,  potash  salts,  bone, 
phosphate  rock,  super  phosphates,  etc.  Tankage 
and  the  guanos  are  ^*  simples,''  as  they  are  the  bases 
of  manufactured  brands.  There  are  low  and  high 
grades  of  the  ** simples"  as  well  as  of  brands,  and 
guarantees  should  always  be  obtained  by  the  buyer. 

Sometimes  these  materials  can  be  purchased 
cheaper  separately  than  when  mixed.  Such  is  the 
case  if  the  buyer  is  near  a  seaport  or  near  the  source 

27 


of  the  material.  The  advantages  are  the  buyer 
knows  what  he  is  getting;  he  buys  only  the  ingre- 
dients he  needs,  and  he  buys  direct.  Such  advantages, 
however,  do  not  always  hold  if  the  quantity  wanted 
is  less  than  a  carload.  Farmers  can  then  club 
together  and  effect  the  saving. 

If,  however,  a  complete  fertilizer  is  needed,  it  is 
better  to  buy  of  a  reliable  manufacturer,  as  the  goods 
are  then  mixed  and  blended  more  evenly  and  cheaply. 
If  several  ingredients  are  needed,  and  these  can  be 
purchased  to  advantage  separately,  it  would  be  better 
to  apply  them  separately  than  to  attempt  home 
mixing,  for  a  shovel  and  a  bam  floor  will  not  mix 
foods  evenly  and  uniformly. 

As  a  rule  home  mixing  pa^^s  when  compared  with 
the  purchase  of  low  grade  brands.  If  the  manufac- 
turer offers  HIGH  GRADE  fertilizers  it  is  time  and 
money  saved  to  use  them. 

WHY  THE  ANALYSIS  DOES  NOT  ADD  TO  ONE  HUNDRED 
PER  CENT. 

The  Vermont  Agricultural  Experiment  Station 
Bulletin  No.  47  says:  **The  question  is  often  asked 
why  the  plant  food  contained  in  a  fertilizer  does  not 
add  up  to  100.  For  instance,  the  average  Vermont 
goods  this  year  contain  in  a  hundred,  2.22  pounds 
nitrogen,  10.93  pounds  total  phosphoric  acid  and 
3.46  pounds  of  potash,  a  total  of  16.61  pounds.  Of 
what  did  the  other  83.39  pounds  consist,  and  is  it 

28 


L/roKUV^ 


needed  for  plant  food?    It  will  be  remembered  that 

nitrogen  is  a  gas,  and  phosphoric  acid  and  potash 

respectively  strong  acid  and  alkali,  and  that  they 

can  only  be  useful  in  combined  forms.    If  medium 

grade  materials  were  used  in  the  manufacture  of  the 

average  fertilizer,  as  stated  above,  it  might  be  made 

up  about  as  follows : 

440  pounds  of  organic  matter  (blood,  tankage,  etc.) 

850  pounds  of  ground  S.  C.  rock  and  sulphuric  acid. 

llo  pounds  of  muriate  of  potash. 

1400  lbs. 

This  would  leave  600  pounds,  or  30  per  cent,  of 
the  gross  weight  in  every  ton  for  moisture,  dirt  and 
useless  material  on  which  freight,  mixing  and  bagging 
expenses,  storage,  etc.,  must  be  paid  by  the  consumer. 

A  complete  analysis  of  the  above  1400  pounds 
would  probably  resemble  the  following : 

Water 16.0    (Combined  with  organic 

matter  and  sulphuric  acid) 

Nitrogen.. 2.2 

Phosphoric  acid 10.6 

Potash 2.9 

Volatile  and  organic    33.0  (Combined  with  nitrogen) 

Gypsum 16.0  (Formed    by     action     of 

sulphuric  acid  on  rock.) 

Lime 7.1  (Leftcombined  withphos- 

phoric  acid.) 

Sand 4.0  (Impurity    phosp.   rock.) 

Chlorine  and  Salts..       3.0  (Combined  with  potash.) 
Miscellaneous 5.2 

100.0 

29 


Of  the  ten  substances  which  compose  the  above 
100  per  cent,  only  three  are  of  interest  to  the  farmer. 
The  value  of  the  whole  ton  is  based  on  the  value  of 
the  nitrogen,  phosphoric  acid,  and  potash,  only. 

In  raw  bone,  for  example,  it  is  impossible  to  give 
a  farmer  the  S%  nitrogen  and  the  24%  phosphoric 
acid  contained  without  giving  him  the  73%  of  lime, 
gelatines  and  fats,  etc.,  found  in  bone,  for  these  sub- 
stances are  in  combination  and  the  process  of  separ- 
ation would  be  too  costly. 

HOW  TO  UNDERSTAND  A  FERTILIZER  ANALYSIS. 

Manufacturers  often  state  the  analysis  of  their 
fertilizers  in  a  confusing  way.  They  use  two  terms 
to  express  the  same  thing.  Nitrogen  and  ammonia 
both  mean  one  thing,  and  the  analysis  should  read, 
for  example,  **nitrogen  4.95%  equal  to  ammonia 
6%,**  showing  that  there  is  not  both  the  4.95%,  and 
the  6%,  but  only  one  or  the  other.  That  the  one 
repeats  the  other.  Multiply  the  percentage  of  am 
monia  by  .825  and  the  result  will  be  the  equivalent 
in  nitrogen,  as  for  example,  6%  ammonia  X  .825= 
4.95%  nitrogen.  It  takes  4.95%  nitrogen  to  equal 
6%  ammonia.  In  figuring  the  value  of  a  ton  in 
dollars  and  cents,  nitrogen  from  blood  or  nitrate  of 
soda  has  a  market  value  of  16  cents  per  pound,  while 
its  equivalent  in  ammonia  is  worth  only  13%  cents 
per  pound.  Only  one  should  be  included  in  the 
estimate. 

30 


And  so  with  the  terms  bone  phosphate  and  phos- 
phoric acid.  The  phosphoric  acid  comes  from  the 
bone  phosphate.  For  example,  it  takes  30%  of  bone 
phosphate  (sometimes  called  **bone  phosphate  of 
lime**)  to  make  13.74%  of  phosphoric  acid.  When 
both  terms  are  employed  by  the  manufacturer  the 
words,  ^^equal  to**  should  be  used,  thus:  **Bone 
phosphate  of  lime,  30%,  equal  to  phosphoric  acid, 
13.74%,**  which  means  that  the  manufacturer  used 
600  pounds  of  bone  phosphate  or  bone— 30%  of  the 
ton — to  obtain  13.74%  of  phosphoric  acid. 

Multiply  the  percentage  of  bone  phosphate  by 
.458  and  the  result  will  be  the  equivalent  in  phos- 
phoric acid,  thus:  30%  bone  phosphate  of  lime 
X  .458=13.74%  phosphoric  acid. 

In  estimating  the  value  of  a  ton  in  dollars  and 
cents,  phosphoric  acid  from  fine  bone  is  worth  about 
5^2  cents  per  pound,  while  its  equivalent  in  terms  of 
bone  phosphate  is  worth  only  2^  cents  per  pound. 
Only  one  should  be  included  in  the  estimate. 

Where  the  **soluble,**  the  *  ^reverted,**  and  the 
*  insoluble,**  and  the  ^^total**  phosphoric  acid  are  all 
given,  it  is  understood  that  the  ^^total**  is  made  up 
of  the  first  three  mentioned. 

The  sulphate  and  muriate  of  potash  will  analyze 
in  round  numbers  about  50%  actual  potash  (some- 
times expressed  as  K2O).  In  other  words,  it  takes 
two  pounds  of  sulphate  or  muriate  of  potash  to 

31 


make  one  pound  of  actual  potash  (K2O).  When  an 
analysis  states:  * 'Sulphate  of  potash  8%,  actual 
potash  4^%,^^  it  means  simply  that  there  is  only  4% 
of  potash  in  the  ton,  or  80  pounds,  and  that  the 
manufacturers  used  S%  or  160  pounds  of  sulphate 
of  potash  to  get  it.  The  actual  potash  is  worth 
about  six  cents  per  pound,  while  the  sulphate  is 
worth  only  three  cents  per  pound. 

When  both  terms  are  used  in  stating  the  analysis, 
only  one  of  them  should  be  included  in  the  estimate 
of  the  value  of  the  ton. 

COMMERCIAL  VS.  AGRICULTURAL  VALUE. 

Farmers  frequently  confound  the  agricultural 
and  commercial  value  of  a  fertilizer.  If  one  is  high  it 
does  not  necessarily  imply  that  the  other  must  be. 

The  commercial  value  of  any  commodity  is  its 
market  price,  its  purchase  price,  and  depends  entirely 
upon  '^supply  and  demand.'' 

The  agricultural  value  of  a  fertilizer  is  its  ability 
to  improve  the  fertility  of  the  soil  and  the  condition 
of  the  crop  in  question. 

As  an  illustration,  suppose  a  steady,  long-lived 
food  were  wanted  for  some  perennials  as  an  orchard, 
blood  would  answer  the  purpose  while  nitrate  of 
soda  would  be  soon  exhausted  or  lost  by  leaching. 
Now,  while  the  price  of  both  nitrate  and  blood  is 
about  the  same,  ($55.00  per. ton)  the  agricultural  value 

32 


of  blood  is  far  greater.  If  a  quickly  acting  manure 
was  wanted  the  nitrate  of  soda  would  have  the 
higher  agricultural  value. 

Again,  if  phosphoric  acid  was  not  needed  for  a 
particular  soil  and  crop,  it  would  then  have  no  agri- 
cultural value  in  that  case,  but  would  still  have  a 
market,  or  commercial,  value. 

In  the  selection  of  a  fertilizer,  the  agricultural 
value  should  be  considered  first  and  the  commercial 
value  second.  Good  results  are  of  first  imx3ortance 
as  they  repay  the  cost  man3''  times. 


THE  USE  OF  FERTILIZERS. 

In  order  to  use  fertilizers  intelligent^,  it  is 
necesssar^^  to  know  the  specific  action  of  the  three 
plant  foods,  nitrogen,  phosphoric  acid,  and  potash, 
and  v^hen  and  how  to  apply  them.  So  far  as  the 
author  knows,  there  have  never  been  any  exhaustive 
experiments  made  to  this  end  in  California  w^ith 
special  reference  to  citrus  fruits.  However,  by  the 
help  of  agricultural  colleges,  certan  general  principles 
have  been  discovered,  and  certain  conclusive  results 
obtained,  in  connection  w^ith  deciduous  fruits  and 
other  plants,  w^hich  are  a  guide  and  help  in  citrus 
culture.  The  few  experiments  w^hich  have  been  made 
with  various  fertilizers  on  citrus  trees  confirm  these 
same  general  principles.    The3^  will  be  briefly  stated. 

33 


EFFECT    OF    NITROGEN. 

The  presence  of  available  nitrogen  is  shown  by  a 
dark,  healthy,  green  color  of  leaves  and  stems. 
Grov^th  is  vigorous.  The  feeding  power  of  the  plant 
is  increased.  If  an  excess  of  nitrogen  is  available  at 
the  time  of  flowering,  and  the  supply  of  phosphoric 
acid  insufficient,  the  bud  and  bloom  and  fruit  will  be 
imperfect  and  the  total  amount  of  fruit  lessened.  The 
fruit  will  then  be  rough  and  thick-skinned.  Constant 
use  of  stable  manure,  without  the  addition  of  phos- 
phoric acid,  will  produce  thick-rind  fruit,  as  manure  is 
relatively  high  in  nitrogen.  The  size  of  fruit  may  be 
increased  by  nitrogen.  A  lack  of  nitrogen  is  shown 
by  yellow  trees  and  small  growth,  or  lack  of  vigor. 
Nitrogen  will  not  give  its  best  effect  unless  phos- 
phoric acid  is  present. 

EFFECT    OF    PHOSPHORIC    ACID. 

Phosphoric  acid  helps  a  plant  to  assimilate  other 
plant  foods.  It  is  also  essential  to  the  final  maturity 
of  the  plant  or  its  seed  production,  and  hastens  this 
maturity,  if  abundant  and  available  at  blossoming 
time.  Although  the  navel  orange  contains  no  seed, 
phosphoric  acid  is  as  essential  as  though  it  did. 
What  usually  thus  goes  into  seed  is  needed  elsewhere 
in  the  development  of  the  fruit. 

If  maturity  is  hastened  by  the  presence  of  an 
abundance  of  available  phosphoric  acid  at  the  time 

34 


of  blossom,  the  early  ripening  of  the  orange  can  be 
likewise  effected. 

Phosphoric  acid  will  not  give  its  best  effect  unless 
there  is  some  nitrogen  present.  Plants  well  supplied 
with  phosphorous,  vegetate  faster  and  are  earlier. 
If  an  over  abundance  of  nitrogen  is  making  fruit 
rough  or  '* puffy,''  phosphoric  acid  will  correct  this. 
Its  tendency  is  to  make  thin-skinned,  smooth  fruit. 

EFFECT  OF  POTASH. 

Potash  is  necessary-  to  the  full  development  of 
the  wood  of  the  tree.  If  potash  is  wanting,  the  wood 
will  not  mature,  and  is  subject  to  frost  and  disease ; 
neither  can  immature  wood  carry  much  fruit.  Potash 
aids  in  the  formation  and  transfer  of  starch,  first  to 
the  leaves  and  from  thereto  the  flesh  of  the  fruit, 
which  would  be  imperfect  otherwise.  The  best 
authorities  agree  that  potash  increases  the  sweetness 
of  fruits. 

Plants,  undoubtedly,  begin  their  growth  in  the 
spring  on  the  food  that  was  stored  in  their  tissues 
the  previous  fall.  Potash  is  largely  the  source  of 
this  stored  food,  and  is  consequently  necessary  to 
the  full  growth  and  health  of  the  tree. 

It  is  generally  admitted,  however,  that  applica- 
tions of  potash  are  unnecessary  in  most  California 
soils.  Many  cases  are  reported  in  which  heavy 
applications  of  wood  ashes  gave  no  appreciable 
results.   If  the  land  in  question  has  been  continuously 

35 


cropped  many  years,  as  in  a  fifteen  or  twenty  ^^ears" 
old  orchard,  the  potash  question  should  be  carefully 
investigated. 

GENERAL    PRINCIPLES. 

In  a  general  wa^^,  both  phosphoric  acid  and 
potash  influence  the  quality  and  fineness  of  the  fruit, 
while  nitrogen  produces  the  vegetable  tissue,  such  as 
the  skin  and  pulp  of  fruit,  and  leaves  and  bark  of 
trees.  The  juice  and  seed  and  smoothness  and  the 
number  of  the  fruits  can  be  increased  by  phosphoric 
acid  and  potash.  The  size  and  coarseness  and  large 
growth  and  late  maturity  can  be  secured  by  the 
extensive  use  of  nitrogen.  These  effects  are  noticeable 
only  wrhen  there  is  an  excess  of  one  element  and  a 
deficiency  of  the  others. 

AVOIDING   PURCHASES    OF    UNNECESSARY    FERTILIZERS. 

Knowing  the  specific  effect  of  the  three  essential 
plant  foods,  as  just  stated,  and  by  observing  the  con- 
dition of  an  orchard,  a  grower  may  frequently  avoid 
the  purchase  of  unnecessary  plant  food. 

Bottomlands  are  usually  rich  in  nitrogen.  Sandy 
soils  are  apt  to  lack  potash.  Clay  soils  usually  con- 
tain much  potash,  etc.  Coarse,  thick-rind  fruit,  with 
deep  green  color  of  leaves  and  a  too  vigorous 
growth,  may  indicate  that  nitrogen  could  profitably 
be  omitted  one  season.  An  over  abundance  of 
smooth  fruit  on  yellow  trees  of  slow  growth  may 
indicate  an  excess  of  phosphoric  acid  tor  the  nitrogen 

36 


present,  or  a  lack  of  nitrogen.  Iron  is  as  essential  as 
nitrogen  to  green  leaves  and  stems,  so  yellow  foliage 
may  be  caused  by  absence  of  iron  as  ^vell  as  nitrogen. 
The  amount  of  iron  necessary  for  green  foliage  is  so 
small,  that  lack  of  nitrogen  is  usually  the  cause  of 
3^ello\v  color  in  citrus  orchards. 

TIME  TO  APPLY  FERTILIZERS. 

In  the  book  of  nature  we  read  that  growth  is 
dormant  for  some  months  preceding  the  blossom  and 
fruit-setting  period.  This  is  naturally  the  time  of 
most  moisture  in  soils,  which,  w^ith  root  acids  and 
fermentation,  are  rendering  available  and  unavail- 
able plant  foods  natural  to  the  soil.  So,  when  the 
important  time  of  blossom  comes,  the  plants  have 
their  greatest  store  of  available  plant  food  to  draw 
upon.  Why,  then,  should  not  fertilizers  be  applied 
long  enough  before  the  blossom  time  to  become 
available  ? 

Nitrate  of  soda  requires  the  least  time.  Blood 
requires  more  time  than  nitrate,  and  raw  bone  more 
time  than  blood.  Coarse  bone,  and  hoof  arid  horn 
meal,  are  slowest  in  their  action.  Acidulated  phos- 
phate acts  more  quickly  than  any  other  form  (that 
is  the  soluble  portion.)  Steamed,  fine  ground  bone, 
used  with  some  ammoniate,  is  next  in  order,  while 
fatty,  raw^  bone  takes  still  more  time  to  decompose. 

Many  apply  a  part  of  the  fertilizer  in  early  sum- 
mer.    This  is  intended  to  feed  the  later  growth  of 

37 


tree  and  crop  and  lessen  the  risk  of  loss  by  winter 
^waste  waters. 

Acidulated  forms  should  always  be  applied  just 
before  an  irrigation  or  rain,  for  then  the  w^ater  will 
carry  the  soluble  portion  to  the  deepest  roots, 
w^herever,  in  fact,  water  can  go.  There  reversion  to 
insolubility  may  and  probably  does  occur  in  a  few 
days,  but  the  phosphoric  acid  is  where  the  roots  can 
act  on  it  directly. 

Nitrate  of  soda  should  not  be  applied  in  late  fall 
or  winter  months  while  growth  is  dormant,  as  it 
would  probably  be  leached  away  before  the  tree  could 
take  it  up.  Organic  forms  should  be  applied  in 
January  or  before. 

AMOUNT  TO  APPLY. 

As  to  the  quantity  to  apply,  no  one  can  tell  this 
w^ithout  careful  experiment.  Much  depends  upon  the 
character  of  the  soil,  the  condition  and  age  of  trees, 
and  variety  of  fruit  in  question.  The  most  vigorous 
grow^th  requires  the  most  food.  Each  grower  must 
be  his  OAvn  authority. 

A  pound  of  high  grade  fertilizer  to  each  year  of 
age  of  the  tree  is  the  amount  usually  recommended 
for  navel  orange  trees  in  full  bearing.  Orchards  other- 
wise well  cared  for,  supplied  with  this  amount^ 
increase  their  yield  each  year.  Usually,  however, 
where  two  pounds  per  3^ear  of  age  of  tree  is  used,  the 

38 


yield  of  navel  oranges  is  sufficient  to  warrant  such 
application  with  profit. 

This  is  particularly  true  of  trees  over  ten  years 
old.  If  the  fertilizer  is  low  grade,  the  amount  used 
should  be  doubled. 

METHOD    OF    APPLICATION. 

The  best  method  of  application  is  undoubtedly 
by  drill,  on  account  of  its  labor  saving  and  uniformity. 
Though  not  over  five  inches  deep,  the  drill  covers  the 
fertilizer,  which  can  be  placed  deeper  by  subsequent 
plowing.  The  use  of  drill  obviates  the  unpleasant- 
ness of  applying  in  any  winds  which  may  prevail.  No 
hand  process  is  so  uniform  or  inexpensive,  though 
some  other  methods  place  the  fertilizer  deeper.  It  is 
well  worth  the  extra  cost  to  hire  a  hand  to  follow 
each  plow  furrow  and  place  the  fertilizer  that  depth. 

STABLE  MANURE. 

An  average  analysis  ot  one  ton  of  horse  manure 
would  be : 

Nitrogen— 0.50%  or  10  lbs.  of  a  ton  at  16c ..$1.60 

Phosphoric  acid — 0.25%  or51bs.  of  atonat6c...      .30 
Potash— 0.40%  or  9.6  lbs.  of  a  ton  at  6c 58 


$2.48 

The  commercial  value  of  the  plant  food  is  then 

about  $2.50  per  ton.   Barn  3^ard  manure,  when  cared 

for  properly,  is  a  most  profitable  form  of  fertilizer, 

39 


because  of  its  htimlc  and  mulch  value.  It  is  a  bi- 
product  of  every  ranch,  costs  nothing,  and  is  virorth 
about  $2.50  per  ton  for  the  actual  plant  food  con- 
tained. In  dry  countries  it  has  a  still  greater  value 
in  its  moisture-saving  properties.  As  a  source  of 
humus  it  is  worth  considerably  more  than  its  plant 
food  value. 

The  more  decomposed  the  manure,  the  more 
available  is  its  plant  food.  If,  however,  decomposi- 
tion is  too  rapid,  the  nitrogen  escapes  in  the  air  as 
ammonia,  and  humus-forming  matter  is  destroyed. 
High  temperatures  produce  rapid  decomposition, 
especially  in  a  loose  heap,  so  that  the  rate  of  decay 
may  be  regulated  b3^  compacting  the  heap  and 
sprinkling  with  water  to  exclude  the  air  and  reduce 
the  temperature.  If  compacted  too  tightly,  decom- 
position may  be  too  slow.  Moderate  fermentation 
is  the  object  desired.  Loss  of  nitrogen,  as  ammonia, 
may  be  detected  by  the  strong  odor  arising  from  the 
heap. 

If  it  is  desired  to  obtain  the  benefits  of  the  plant 
food  in  manure  quickly,  it  should  be  stored  under 
cover  to  prevent  loss  by  leaching,  and  the  temperature 
kept  down  by  frequent  wetting,  and  air  excluded  by 
settling  the  heap;  decomposition  may  thus  take 
place  with  a  minimum  loss  of  ammonia.  If  from  one 
to  two  pounds  of  either  gypsum,  lime,  or  sulphate  of 
potash  be  sprinkled    on    the   heap  each  day  as  it 

40 


accumulates,  the  ammonia  is  prevented  from  escap- 
ing. The  gypsum  must  be  moist  for  this  use  to  be 
effective. 

If,  however,  it  is  not  desired  to  get  the  benefits  of 
plant  food  quickly,  the  manure  had  better  be  applied 
fresh  and  incorporated  with  the  soil  at  once.  Decom- 
position may  be  slower  in  such  cases,  but  loss  of 
ammonia  is  surely  prevented  and  a  much  better 
mulch  obtained. 

*^  Humus  is  not  only  the  principal  source  of  nitro- 
gen in  soils,  but  it  influences  to  a  marked  extent  the 
available  potash  and  phosphoric  acid.  Humus- 
forming  materials,  like  green  manures  and  yard 
manure,  have  the  power,  when  they  decompose  in 
the  soil,  of  combining  with  the  potash  and  phosphoric 
acid  of  the  soil  and  thus  converting  them  into  forms 
which  are  readily  utilized  b^^  the  plants.^'  (From 
Experiment  Station  Work,  V.  of  the  U.  S.  Department 
of  Agriculture. ) 

GREEN   MANURING. 

The  object  of  sowing  the  leguminous,  or  pod- 
bearing  plants  is  four-fold. 

1st.  To  obtain  the  nitrogen  which  they  produce 
by  their  growth. 

2d.  To  set  free  unavailable  plant  food  hj  the 
action  of  their  roots. 

3d.  To  lighten  the  soil  by  plowing  them  under 
while  green.  The  capacity  of  soils  for  absorbing  and 
retaining  moisture  is  thus  increased,  part  of  the  cost 

41 


of  nitrogen  is  saved,  and  danger  of  washing  by 
Avinter  rains  is  lessened. 

^th.  For  humus,  which  is  always  necessary  for 
any  form  of  crop. 

The  Canadian  field  pea  is  the  most  popular  plant 
for  this  purpose.  Beans  and  clover  are  also  used. 
Barley  and  other  grains  have  not  the  same  power  to 
absorb  nitrogen  from  the  air,  and,  unless  turned  un- 
der green,  dry  out  the  soil  and  render  it  hard  to 
work.  Barley  is  beneficial  as  far  as  its  roots  set  free 
unavailable  forms  of  potash  and  phosphoric  acid. 

The  green  manure  wanted  by  orange  growers  is 
one  that  will  grow  quickly,  as  California  winters  are 
short  and  dry,  and  growers  cannot  afford  to  let  the 
ground  rest  undisturbed  very  long. 

HUMUS  FERTILIZERS— NECESSITY  OF  ORGANIC  MATTER. 

Humus  is  decaj^ed  organic  matter.  It  is  necessary 
for  fertility,  because  all  the  nitrogen  in  soils  comes 
from  either  an  animal  or  vegetable  source.  (Very 
minute  quantities  are  absorbed  from  the  air  as 
ammonia  and  as  nitrogen,)  The  nitrates  come  from 
humus.  They  are  \vater  soluble  and  can  be  taken  up 
by  the  roots.    Thus  the  plant  gets  its  nitrogen. 

All  fertile  soils  are  rich  in  organic  matter.  The 
exceeding  richness  of  new  lands  is  due  to  the  humus 
deposited  by  succeeding  crops  for  generations.  This 
is  true  of  both  the  high  mesa  and  the  valley  land.  It 
is  possible  to  use  some  chemical  form  of  nitrogen  and 

42 


raise  a  plant,  but  it  is  expensive,  requires  close  watch 
ing,  and  is  not  practical.  The  nitrogen  from  organic 
fertilizers  is  yielded  to  the  plant  gradually,  with 
greater  certainty,  and  is  more  lasting. 

Organic  manures,  whether  of  blood  and  bone,  or 
stable  manure,  or  green  cover  crops,  not  only  furnish 
nitrogen  to  plant  life,  but  their  decay  generates 
several  well  known  acids,  notably  carbonic,  which 
combine  with  soil  moisture  and  dissolve  other  forms 
of  plant  food.  Without  these  acids,  phOvSphorous, 
potash,  and  other  necessary  elements  would  not  be 
so  available  to  the  plant.  Direct  root  and  water 
action  would  then  have  to  do  the  work  alone,  and 
the  plant  w^ould  not  thrive  so  w^ell.  Humus  influ- 
ences the  availability  of  the  phosphoric  acid  and 
potash  and  converts  them  into  forms  more  readily 
utilized  by  the  plant. 

Organic  fertilizers  lighten  soils.  Their  decay 
leaves  the  soil  open  and  porous.  More  oxygen  is 
thus  admitted,  which  gives  more  life  to  the  micro-- 
organisms  which,  after  all,  are  the  cause  of  all 
fertility.  Better  cultivation  is  possible  in  such  soils. 
Light,  porous  soils  are  more  retentive  of  moisture. 
Thus,  organic  matter  literally  builds  up  a  soil.  It 
increases  its  depth.  A  '*  worn-out'*  soil  is  simply  a 
soil  devoid  of  humus.  It  is  lifeless.  Liberal  applica- 
tions of  organic  matter  restore  it  and  change  it  from 
a  tax  to  an  income. 

43 


Humus-forming  materials  are,  therefore,  necessary 
to  successful  and  practical  farming.  The  best  results 
from  inorganic  fertilizers,  such  as  rock  and  acid 
phosphates,  Thomas  slag  and  sulphate  of  potash, 
are  obtained  when  they  are  used  with  manure,  or 
blood,  or  blood  and  bone,  or  a  green  cover  crop 
turned  under. 

CULTIVATION   AND   FERTILIZERS. 

Cultivation  increases  the  availability  of  fertilizers 
by  aiding  nitrification  and  by  saving  soil  moisture. 
All  organic  forms  must  first  decay  and  then  be  turned 
into  nitrates  (nitrification),  and  other  salts  before 
water  can  carr\^  their  elements  to  the  roots  of  plants. 

The  decomposed  matter  (humus)  is  attacked  by 
nitrifying  bacteria  and  these  require  oxygen  for  their 
work.  Cultivation  increases  this  supply  of  ox^^gen 
«o  that  nitrification  proceeds  faster,  and  better 
growth  results.  The  more  frequent  and  deep  the 
cultivation,  the  better  the  nitrifying  bacteria  can 
work.  The  size  of  fruit  may  be  increased  in  this  way, 
or  a  short  season  made  equal  to  a  long  one. 

This  principle  of  aiding  nitrification  applies  to  all 
forms  of  animal  and  vegetable  fertilizers  such  as  yard 
manure,  blood,  raw  bone,  guano,  tankage,  and  peas 
or  clover,  planted  for  their  fertilizing  value  when 
ploughed  under. 

Frequent,   deep  cultivation  increases  the  supply 
44 


of  water  in  soils.  Several  well-known  acids,  result- 
ing from  decomposition,  unite  with  soil  moisture  and 
dissolve  what  ordinary  water  wall  not.  Insoluble 
forms  of  fertilizers,  such  as  phosphate  of  lime  and 
silicate  of  potash,  are  probably  thus  made  available 
to  the  plant. 

Moist  soils  swell  and  are  more  permeable.  Roots 
can  develop  faster  in  them,  and  the  fertilizers,  applied 
to  the  top  six  inches,  as  they  gradual^  dissolve,  can 
be  carried  more  easily  and  deeply,  increasing  the 
feeding  area  of  the  roots  and  the  development  of  the 
plant. 

IRRIGx\TION  AND   FERTILIZERS. 

Plants  can  take  up  food,  only  when  it  is  provided 
in  solution.  The  food  may  be  dissolved  by  water,  or 
by  direct  root  action,  or  by  the  process  of  fermenta- 
tion, which  is  almost  constant  in  all  soils.  In  either 
case  \vrater  is  essential,  and  the  common  carrier,  and 
the  w^ay  in  which  it  is  used,  seriously  affects  the  re- 
sults of  fertilization.  Especially  is  this  true  because 
the  top  foot  of  soil  contains  the  most  valuable 
fertilizing  ingredients. 

There  are  three  kinds  of  water  in  soils:  free 
water,  which  moves  by  gravity ;  hygroscopic  water, 
detectable  only  by  laboratory  methods  even  in  the 
dryest  earth,  and  capillary  water,  which  moves  by 
the  power  of  attraction  between  particles  of  matter. 
This  capillary  water  is  what  plants  feed  and  depend 

45 


upon  mainly.  It  travels  up  and  down  and  sideways, 
carrying  with  it  the  soluble  fertilizers. 

As  moisture  evaporates  at  the  surface,  it  is  con- 
stantly supplied  from  below  by  the  capillary 
movement.  The  dissolved  fertilizers  contained 
remain  on  the  surface  after  the  water  evaporates ; 
hence  they  accumulate  so  that  top  soils  are  always 
the  richest.  The  next  rain  or  irrigation  carries  the 
plant  food  down  only  to  rise  again  as  evaporation 
progresses  at  the  surface.  There  is  thus  an  oscillation 
of  water  up  and  down  many  times  a  year. 

Certain  forms  of  fertilizers,  such  as  the  nitrates 
{both  soda  and  potash)  ammonium  sulphate,  the 
sulphate  of  potash,  and  the  acid  and  super-phos- 
phates are  easily  carried  by  water.  If  applied  just 
previous  to  an  irrigation  they  go  to  the  deepest 
roots,  wherever  water  can  go.  If  there  is  any  waste 
water  a  part  of  them  is  lost. 

If  the  grade  at  the  flume  is  very  steep  for  fifty  or 
a  hundred  feet,  the  trees  in  that  space  will  be  the 
first  to  turn  yellow,  although  they  are  nearest  the 
flume  and  received  the  most  water.  The  nitrates 
have  been  washed  to  lower  levels.  Manure  or  straw 
should  be  used  in  such  places  so  that  the  water  will 
move  more  slowly  and  the  nitrates  retained  where 
they  belong. 

On  account  of  the  solubilit^^  of  many  forms  of 
plant  food,  irrigation  water  should  be  handled  very 

46 


carefully.  Do  not  turn  a  heavy  head  of  water  into  a 
furrow  until  after  the  furrow  is  soaked  a  little  and 
the  fine  earth  compacted.  This  will  lessen  washing. 
The  ideal  movement  of  water  is  up  and  down,  with 
as  little  movement  on  the  surface  as  possible.  In 
this  way  the  rich  top  soil  with  its  humus  and  fer- 
tilizers will  be  retained  where  it  belongs. 

VALUE  OF  SOIL  ANALYSIS. 

Soil  analyses  are  valuable  for  determining  in  a 
general  way  the  needs  of  a  crop.  The  greater  the 
number  of  samples  examined,  the  more  accurate  will 
be  the  information  obtained.  Very  little  can  be  con- 
cluded from  one  sample.  Taken  in  connection  with 
the  appearance  of  trees  and  vegetation  raised  on  the 
soil,  many  a  useless  expenditure  for  fertilizing  ingre- 
dients may  thus  be  avoided. 

If  samples  of  soil  be  taken  according  to  the  direc- 
tions of  the  State  Experiment  Station  the  results 
may  be  relied  upon  as  indicating  that  soil's  capacity 
for  various  crops.  This  information,  with  the 
owner's  knowledge  of  previous  treatment,  together 
with  the  appearance  of  the  vegetation  and  growth 
gives  a  pretty  thorough  diagnosis.  Each  of  these 
sources  of  information  acts  as  a  check  or  supplements 
the  other  two. 

Soil  analysis  should  be  interpreted  by  an  expert, 
for  where  Ho  of  1  %  would  be  considered  a  sufficiency 

47 


of  some  elements,  it  would  be  regarded  as  a  deficiency 
of  other  elements.  A  soil  containing  %  of  1%  humus 
is  lacking  in  that  substance,  while  that  amount  of 
potash  or  lime  would  be  considered  ample  for 
fertility. 

Again,  soil  analyses  ma3^  reveal  the  presence  of 
some  poison,  such  as  carbonate  of  soda,  or  chlorine, 
in  the  midst  of  otherwise  fertile  conditions.  An 
excess  of  either  acid  or  alkali  can  likewise  be  deter- 
mined. Plant  food  may  be  present  in  abundance  and 
yet  the  results  be  unsatisfactor3^  on  account  of  poor 
cultural  conditions.  This,  also,  soil  analysis  would 
reveal. 

Whenever  there  is  uncertainty  about  the  needs  of 
crops  or  orchard,  soil  analyses  should  alwa^^s  be 
taken.  One  element,  only,  may  be  lacking  and  thus 
discovered,  and  the  purchase  of  the  element  unneces- 
sary^ be  avoided.  The  State  Experiment  Station  has 
advised  farmers  that  sufficient  potash  is  present  in 
nearly  all  California  soils.  General  experience  has 
confirmed  this  statement,  thus  saving  the  farmers 
many  dollars  annually. 


48 


INDEX. 

Acidulated  Phosphates 11 

Agricultural  Value 32 

Analysis  Adding  to  100  per  cent 28 

Analysis  of  Fertilizer,  How  to  Understand 30 

Analysis  of  Soil 47 

Applying  Fertilizers,  Time  for 37 

Applying  Fertilizers,  Amount 38 

Applying  Fertilizers,  Method 39 

Availability 16 

Bone 12 

Commercial  Value 32 

Cultivation,  Relation  to  Fertilizers 44 

Economical  Form  of  Fertilizers 23 

Essential  Plant  Food 6 

Example  of  Fertilizer  v^orth  $5.30  per  ton 24 

Example  of  Fertilizer  worth  $36.00  per  ton 25 

General  Principles,  Effect  of  Fertilizers 36 

High  Grade  Fertilizer,  Example 25 

Home  Mixtures 27 

Humus  (Organic  Matter) 42 

Insolubility,  Desirable .^ 17 

Irrigation,  Relation  to  Fertilizers 45 

Lower  Grade  Fertilizer,  Example 26 

Manure,  Green 41 

Manure,  Stable 39 

Nitrification 10 

Nitrogen,  Cost  of. 22 

Nitrogen,  Effect  of. 34 

Nitrogen  from  Air 10 

Nitrogen,  Sources  of. S 


Organic  Matter  (Humus) 42 

Peas,  Green  Manure 41 

Phosphate    Guanas 14 

Phosphoric  Acid,  CheapCvSt  Form 14 

Phosphoric  Acid,  Cost  of. 22 

Potash,  Effect  of.... 35 

Phosphoric  Acid,  Effect  of 34 

Phosphoric  Acid,  Sources  of. 11 

Plant  Food,  Definition 6 

Potash,  COvSt  of. 23 

Potash,  Sources  of 15 

Purchasing,  General  Principles 24 

Purchase  of  Fertilizers 18 

*' Simples" 27 

Soil  Analysis,  Value  of. 47 

Source  of  Fertilizers 8 

Stable  Manure 39 

Steamed  Bone 12 

Thomas  Phosphate  Slag 13 

Unnecessary  Fertilizers,  Avoiding  Purchase 36 

Use  of  Ferdlizers 33 

EXPLANATORY   NOTE, 

The  statement  made  in  the  paragraph  near  the  top  of 
page  12,  that  the  insoluble  form  of  phosphoric  acid  has 
"no  commercial  value"  should  be  modified.  State  agri- 
cultural stations  usually  attribute  some  commercial  value 
to  this  form  of  phosphoric  acid,  say  about  2  cents  per 
pound,  while  the  water  soluble  form  would  be  regarded  as 
worth  considerably  more.  The  agricultural  value  of 
insoluble,  or  tri-basic,  phosphoric  acid  is  very  much  greater 
than  the  commercial  value  or  the  station  value.  (See  also 
'*  Cheapest  Form  of  Phosphoric  Acid,"  page  14,  and 
"Commercial  vs.  Agricttlt»rai4Jalue,"  page  32.) 


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